Bortezomib, Fluorouracil, and External-Beam Radiation Therapy in Treating Patients With Stage II, Stage III, or Stage IV Rectal Cancer

DISEASE CHARACTERISTICS:

* Biopsy confirmed diagnosis of adenocarcinoma of the rectum meeting 1 of the following clinical staging criteria:

  * T3-T4, N0, M0 (stage II disease)

    * T4 disease defined as tumor fixed on examination or involving adjacent pelvic structures, such as the sidewall, bladder, uterus, prostate, or small bowel by ultrasound or CT scan
  * Any T, N1-2, M0 (stage III disease)
  * Any T, any N, M1 (stage IV disease)
  * Recurrent disease (any prior stage)
* Candidate for local palliative therapy or curative resection of metastatic disease
* Previously treated CNS disease allowed provided it is stable for \> 3 months

PATIENT CHARACTERISTICS:

* ECOG performance status 0-2
* Life expectancy \> 3 months
* Adequate nutrition
* WBC ≥ 4,000/mm³
* ANC \> 2,000/mm³
* Platelet count ≥ 100,000/mm³
* Creatinine ≤ 1.5 mg/dL OR creatinine clearance ≥ 30 mL/min
* Bilirubin ≤ 1.5 mg/dL
* Not pregnant or nursing
* Negative pregnancy test
* Fertile patients must use effective contraception
* No serious medical or psychiatric illness that would limit study compliance or limit survival to \< 2 years
* No history of refractory congestive heart failure or cardiomyopathy
* No active coronary artery disease, myocardial infarction within the past 3 months, or cerebrovascular accident within the past 3 months
* No peripheral neuropathy ≥ grade 2
* No hypersensitivity to bortezomib, boron, or mannitol

PRIOR CONCURRENT THERAPY:

* More than 1 week since prior major surgery
* More than 28 days since prior investigational agents
* Prior chemotherapy allowed
* No prior pelvic radiotherapy (for treatment of any pelvic malignancy)
* No concurrent herbal medication (excluding vitamin and mineral supplements)
* No concurrent filgrastim (G-CSF) or sargramostim (GM-CSF)